C++: show private field accessor hints with -g and optimization (PR c++/84994)

C++: show private field accessor hints with -g and optimization (PR c++/84994)

gcc/cp/ChangeLog:
	PR c++/84994
	* constexpr.c (constexpr_fn_retval): Make non-"static".
	* cp-tree.h (constexpr_fn_retval): New decl.
	* search.c (direct_accessor_p): Update leading comment.
	(reference_accessor_p): Likewise.
	(field_accessor_p): Replace check that function body is a
	RETURN_EXPR with a call to constexpr_fn_retval.  Fix
	indentation of "field_type" decl.

gcc/testsuite/ChangeLog:
	PR c++/84994
	* g++.dg/other/accessor-fixits-1.C: Move to...
	* g++.dg/torture/accessor-fixits-1.C: ...here.
	* g++.dg/other/accessor-fixits-2.C: Move to...
	* g++.dg/torture/accessor-fixits-2.C: ...here.
	* g++.dg/other/accessor-fixits-3.C: Move to...
	* g++.dg/torture/accessor-fixits-3.C: ...here.
	* g++.dg/other/accessor-fixits-4.C: Move to...
	* g++.dg/torture/accessor-fixits-4.C: ...here.
	* g++.dg/other/accessor-fixits-5.C: Move to...
	* g++.dg/torture/accessor-fixits-5.C: ...here.
	* g++.dg/torture/accessor-fixits-6.C: New testcase.
	* g++.dg/torture/accessor-fixits-7.C: New testcase.
	* g++.dg/torture/accessor-fixits-8.C: New testcase.

From-SVN: r258731